Zooplankton biomass in the ice-covered Weddell Sea, Antarctica.

Boysen-Ennen, E., Hagen, W., Hubold, G. and Piatkowski, Uwe (1991) Zooplankton biomass in the ice-covered Weddell Sea, Antarctica. Marine Biology, 111 . pp. 227-235. DOI 10.1007/BF01319704.

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Abstract

Zooplankton was sampled by a Rectangular Midwater Trawl (RMT 1 + 8) in Weddell Sea surface waters (0 to 300 m) between 66 and 78°S during austral summer (February – March 1983). Sixty-nine taxa including different developmental stages were considered and divided into 16 size classes between <1 and >39.5 mm length. Biomass was determined by taxon and size class for three different meso- and macroplankton communities in the oceanic region, on the northeastern shelf and on the southern shelf of the Weddell Sea. The highest biomass of 11.2 mg DW m−3 (3.4 g DW m−2) was found in the northeastern shelf community (70 to 74°S), where juvenile and adultEuphausia crystallorophias accounted for 3.7 mg DW m−3 (1.1 g DW m−2). Although not quantitatively sampled, early copepodite stages (CI to CIII) ofCalanoides acutus andCalanus propinquus ranked second with 2.7 mg DW m−3 (0.8 g DW m−2). Biomass in the northeastern shelf community was concentrated in the size ranges 1 to 4 mm and 19.5 to 39.5 mm. The oceanic community of the central Weddell Sea was dominated by copepods smaller than 5 mm, which made up half of the total oceanic biomass. The tunicateSalpa thompsoni (7.0 to 8.5 mm) was the dominant single species with 1.6 mg DW m−3 (0.5 g DW m−2). Euphausiids, mainly juvenile and adult krillEuphausia superba, comprised 1.2 mg DW m−3 (0.4 g DW m−2). Total standing stock in the oceanic community was 9.4 mg DWm−3 (2.8 g DW m−2). Lowest biomass values were found in the southern shelf community (south of 75°S) with 4.0 mg DW m−3 (1.2 g DW m−2), concentrated in the 1 to 4 mm and 14.5 to 34.5 mm size classes. Abundant species were the pteropodLimacina helicina (1 to 2 mm; 0.7 mg DW m−3; 0.2 g DW m−2) andE. crystallorophias (24.5 to 39.5 mm; 0.9 mg DW m−3; 0.3 g DW m−2). The data reveal that it is essential to distinguish among subsystems in the Southern Ocean. This leads to a better understanding of the structure and function of those pelagic food webs which represent alternatives to the paradigmatic krill-centered system.

Document Type: Article
Keywords: Biomass, Southern Ocean, Austral Summer, Copepodite Stage, Midwater Trawl
Research affiliation: OceanRep > GEOMAR > FB3 Marine Ecology > FB3-EV Marine Evolutionary Ecology
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1007/BF01319704
ISSN: 0025-3162
Date Deposited: 18 Feb 2008 17:27
Last Modified: 06 Jun 2018 12:11
URI: http://oceanrep.geomar.de/id/eprint/1624

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